Sheeran Freya L, Pepe Salvatore
Heart Research, Clinical Sciences, Murdoch Children's Research Institute, and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia; and Department of Surgery at Alfred Hospital, Monash University, Melbourne, Australia.
Heart Research, Clinical Sciences, Murdoch Children's Research Institute, and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia; and Department of Surgery at Alfred Hospital, Monash University, Melbourne, Australia
Am J Physiol Endocrinol Metab. 2016 Aug 1;311(2):E449-60. doi: 10.1152/ajpendo.00127.2016. Epub 2016 Jul 12.
Deficiency of energy supply is a major complication contributing to the syndrome of heart failure (HF). Because the concurrent activity profile of mitochondrial bioenergetic enzymes has not been studied collectively in human HF, our aim was to examine the mitochondrial enzyme defects in left ventricular myocardium obtained from explanted end-stage failing hearts. Compared with nonfailing donor hearts, activity rates of complexes I and IV and the Krebs cycle enzymes isocitrate dehydrogenase, malate dehydrogenase, and aconitase were lower in HF, as determined spectrophotometrically. However, activity rates of complexes II and III and citrate synthase did not differ significantly between the two groups. Protein expression, determined by Western blotting, did not differ between the groups, implying posttranslational perturbation. In the face of diminished total glutathione and coenzyme Q10 levels, oxidative modification was explored as an underlying cause of enzyme dysfunction. Of the three oxidative modifications measured, protein carbonylation was increased significantly by 31% in HF (P < 0.01; n = 18), whereas levels of 4-hydroxynonenal and protein nitration, although elevated, did not differ. Isolation of complexes I and IV and F1FoATP synthase by immunocapture revealed that proteins containing iron-sulphur or heme redox centers were targets of oxidative modification. Energy deficiency in end-stage failing human left ventricle involves impaired activity of key electron transport chain and Krebs cycle enzymes without altered expression of protein levels. Augmented oxidative modification of crucial enzyme subunit structures implicates dysfunction due to diminished capacity for management of mitochondrial reactive oxygen species, thus contributing further to reduced bioenergetics in human HF.
能量供应不足是导致心力衰竭（HF）综合征的主要并发症。由于尚未对人类HF中线粒体生物能量酶的并发活性谱进行综合研究，我们的目的是检查从移植的终末期衰竭心脏获取的左心室心肌中的线粒体酶缺陷。通过分光光度法测定，与非衰竭供体心脏相比，HF中复合物I和IV以及三羧酸循环酶异柠檬酸脱氢酶、苹果酸脱氢酶和乌头酸酶的活性率较低。然而，两组之间复合物II和III以及柠檬酸合酶的活性率没有显著差异。通过蛋白质印迹法测定的蛋白质表达在两组之间没有差异，这意味着存在翻译后干扰。鉴于总谷胱甘肽和辅酶Q10水平降低，探索氧化修饰作为酶功能障碍的潜在原因。在所测量的三种氧化修饰中，HF中蛋白质羰基化显著增加了31%（P < 0.01；n = 18），而4-羟基壬烯醛和蛋白质硝化水平虽然升高，但没有差异。通过免疫捕获分离复合物I和IV以及F1FoATP合酶发现，含有铁硫或血红素氧化还原中心的蛋白质是氧化修饰的靶点。终末期衰竭人类左心室中的能量缺乏涉及关键电子传递链和三羧酸循环酶的活性受损，而蛋白质水平的表达没有改变。关键酶亚基结构的氧化修饰增强意味着由于线粒体活性氧管理能力下降而导致功能障碍，从而进一步导致人类HF中的生物能量减少。
